An electron and a proton are moving on straight parallel paths with same velocity. They enter a semi infinite region of uniform magnetic field perpendicular to the velocity.
Which of the following statement(s) is /are true?

Options

A. They will never come out of the magnetic field region
B. They will come out travelling along parallel paths
C. They will come out at the same time
D. They will come out at different times.

Answer

B, D

Explanation

Both will travel in semicircular path as shown in figure, and they will come out of magnetic field travelling along parallel paths. Time spent by the charged particle to describe semicircular path in the magnetic field is

`t=(pim)/(Bq)` or `tpropm`
As mass (m) of electron is different from that of proton, hence time for their semicircular paths will be different.